Here is my connection (You can check GPIO pinout here):

I used theFTDI GPS adapter cable, solder pads can be used also, just have in mind the TX pad = RX Ublox and RX pad = TX Ublox.

To get information from GPS in the Raspberry Pi (RPi), we will use gpsd.

Open a terminal

Install gpsd:

sudo apt-get install gpsd gpsd-clients python-gps

Setup RPi UART:

sudo nano /boot/cmdline.txt
delete the "ttyAMA0" parameter to have:
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

sudo nano /etc/inittab
comment (add a hash #) the line below "#Spawn a getty on Raspberry Pi serial line" like this:
#T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100

Reboot the RPi to apply the configuration:
sudo reboot

At this moment gpsd program is installed. If any gpsd session is open, stop it by:

sudo killall gpsd

Due to 3DR GPS is configured at 38400 bauds, set the RPi to 38400 bauds will be needed:

stty -F /dev/ttyAMA0 38400

(when RPi reboot baud rate returns to default)

Start gpsd:

sudo gpsd /dev/ttyAMA0 -F /var/run/gpsd.sock

Display GPS data:

cgps -s

When 3DR GPS is fixed, the fix blue led will be blinking and you will get the data like this:

If the GPS is not fixing, try outdoors where you have a clear sky view.